The invention relates to a high flow filter and to certain embodiments that relate to a pleated filter media for use in a high flow compact disc filter arrangement for filtering liquids.
A conventional biological wastewater treatment plant typically incorporates a gravity clarifier at the end of the process, to clean the effluent water to a sufficient level to allow for discharge into a natural body of water such as a lake or river. In regions where water is scarce, it may be desirable to further filter and disinfect the water to allow for safe “reuse” of the water, for example, watering grass on public grounds.
Large gravity-driven drum filter screens can be used to filter the effluent water from the wastewater treatment plant. However, in large scale treatment plants (e.g., one million gallons per day or more) drum filter screens are costly per unit of capacity. In other words, multiple large drum filters, including many filter screens, are required to provide sufficient filter media area to filter the quantity of effluent that must pass through the system.
Disc filters have been employed to increase the surface area of the filter media without increasing the land area required by the screening equipment. For a given flow, a disc filter with flat filter panels employs a geometry which requires less land area than a drum filter with equivalent capacity. Although pump pressure driven strainers can be smaller, flat panel disc filters currently provide the minimum land area required in a gravity-driven filtration system for such applications.
While pleated filter media is commonly used in applications that filter gasses (e.g., air), their use in liquid applications is somewhat limited due to the higher viscosity of the fluids, to low flow uses and liquids containing low solids levels. High flows generate large pressure drops which tend to deform the pleats, and may result in tearing of the media or other loss of function unless managed well by the designers. In particular, pleated filter media has been very difficult to adapt to large scale filtering operations such as those that are commonly employed to filter water in a large water treatment facility. In these applications, the high volume of flow required would require very large surface areas to reduce the volumetric flow per unit area to a level that is acceptable by prior art pleated media. The present invention overcomes these limitations and provides a high flow pleated filter that is substantially smaller and robust than what could be achieved using prior art filters.